Drs. Oz and Roizen: Lack of vitamin D-3 leads to health risks

From October to March, the sun isn't strong enough north of Los Angeles and Atlanta to prod your body into making much vitamin D-3. That endangers your immune system, makes you vulnerable to depression and overeating, weakens your bones and increases your risk for certain cancers. And then there's the newest D-3 alert: Lack of vitamin D-3 in older adults is associated with cognitive decline and Alzheimer's disease.

And while as far as we know there's no chance lack of sunlight will turn you into an underground-dwelling, light-averse Morlock, those are pretty significant, but quite correctable, health risks.

What's the solution? Even if you head to sunnier climes, or live there year-round, chances are you're not outside enough to get the D-3 machine going (90 percent of your time is spent indoors). That's why only a quarter to a third of Americans and Canadians have the recommended minimum blood levels of vitamin D-3. So, we suggest:

Get a vitamin D-3 blood test: If your reading comes back below 50, you need a D-boost plan. (Over 100 may be too high and trigger its own set of problems.)

Choose D-packed foods: Canned salmon dishes up 500 IU of D-3 in every 3-ounce serving. Other good sources: vitamin D-enriched low-fat milk and OJ (100 IU per glass). One study showed that women over 70 who get the most vitamin D from their food were a whopping 77 percent less likely to develop dementia.

Take a supplement: D-3 is the form you want -- 1,000 IU a day; 1,200 if you're 60 plus.

Dr. Mehmet Oz is host of "The Dr. Oz Show," and Dr. Mike Roizen is chief medical officer at the Cleveland Clinic Wellness Institute. For more information go to www.RealAge.com.